Optimising diet decisions and urban agriculture using linear programming

The Environmental Sustainability of Plant-Based Dietary Patterns: A Scoping Review

BACKGROUND

A large part of the existential threat associated with climate change is the result of current human feeding patterns. Over the last decade, research evaluating the diet-related environmental impacts of plant-based diets has emerged, and a synthesis of the available data is now due.

OBJECTIVES

The objectives of the study were as follows: 1) to compile and summarize the literature on diet-related environmental impacts of plant-based dietary patterns; 2) to assess the nature of the data on impacts of plant-based dietary patterns on both environmental parameters and health (e.g., if land use is reduced for a particular diet, is cancer risk also reduced?); and 3) to determine where sufficient data exist for meta-analyses, in addition to identifying gaps within the literature.

METHODS

Global peer-reviewed studies on the environmental impacts of plant-based diets were searched in Ovid MEDLINE, EMBASE, and Web of Science. After removing duplicates, the screening identified 1553 records. After 2 stages of independent review by 2 reviewers, 65 records met the inclusion criteria and were eligible to be used in synthesis.

RESULTS

Evidence suggests that plant-based diets may offer lower greenhouse gas emissions (GHGEs), land use, and biodiversity loss than offered by standard diets; however, the impact on water and energy use may depend on the types of plant-based foods consumed. Further, the studies were consistent in demonstrating that plant-based dietary patterns that reduce diet-related mortality also promote environmental sustainability.

CONCLUSIONS

Overall, there was agreement across the studies regarding the impact of plant-based dietary patterns on GHGE, land used, and biodiversity loss despite varied plant-based diets assessed.

Urban Horticulture for Food Secure Cities through and beyond COVID-19

Sufficient production, consistent food supply, and environmental protection in urban +settings are major global concerns for future sustainable cities. Currently, sustainable food supply is under intense pressure due to exponential population growth, expanding urban dwellings, climate change, and limited natural resources. The recent novel coronavirus 2019 (COVID-19) pandemic crisis has impacted sustainable fresh food supply, and has disrupted the food supply chain and prices significantly. Under these circumstances, urban horticulture and crop cultivation have emerged as potential ways to expand to new locations through urban green infrastructure. Therefore, the objective of this study is to review the salient features of contemporary urban horticulture, in addition to illustrating traditional and innovative developments occurring in urban environments. Current urban cropping systems, such as home gardening, community gardens, edible landscape, and indoor planting systems, can be enhanced with new techniques, such as vertical gardening, hydroponics, aeroponics, aquaponics, and rooftop gardening. These modern techniques are ecofriendly, energy- saving, and promise food security through steady supplies of fresh fruits and vegetables to urban neighborhoods. There is a need, in this modern era, to integrate information technology tools in urban horticulture, which could help in maintaining consistent food supply during (and after) a pandemic, as well as make agriculture more sustainable.

Systemic Design for Food Self-Sufficiency in Urban Areas

This article adopts a systemic approach to address the problem of the operationalization of relationships between actors conducive to food self-sufficiency in urban areas. Through the use of Social Network Analysis (SNA), the literature on urban agriculture was analyzed, detecting eight key trends and topic areas. This information was used to design a generic recursive organizational structure with the identification of the key roles and functions for management and governance in the multi-level and multi-stakeholder relationships of a sustainable urban self-sufficient food production system, inspired by the principles of complexity management and organizational cybernetics. Methodologically, this is the first application that combines the exploratory capability of SNA and the recursive structure of the Viable System Model (VSM) to propose applicable organizational structures in any urban area, suggesting a new route for the study and application of systemic thinking in the development of urban agriculture schemes. However, due to the conceptual nature of this work, this study opens a discussion on how we can rethink interactions to seek continuous adaptation in food self-sufficiency, provide tools that foster inclusion, and adapt to every context to support the relevant actors and academics in urban agriculture.

Productivity, resource efficiency and financial savings: An investigation of the current capabilities and potential of South Australian home food gardens

As the dominant form of urban agriculture (UA) in Australia, existing home food gardens potentially represent a significant resource in the context of future urban food security and sustainability. However, a severe lack of in-field data has hindered our understanding of the form and function of home food gardens which in turn may hinder innovation and improvement. We investigated the productivity, resource efficiency and potential financial savings of home food gardens in South Australia. A group of 34 citizen science participants measured and recorded inputs and outputs from their gardens. Inputs included time spent on various gardening activities, financial costs, and water use. Outputs included crop yields, from which retail value and nutritional content were then derived. The paper outlines a field-demonstrated, comprehensive methodology for continued and consistent data collection for all forms of UA. We found smaller gardens to be more intensive than larger gardens, requiring higher inputs, but also returning higher outputs per unit area. Both productivity and resource efficiency varied among the gardens, and labour requirements were significantly lower than previously estimated. Water use efficiency of the gardens were calculated and found to have comparable water use efficiency to commercial horticulture. Of the gardens involved, we calculated that 65% should break even in five or less years and save money. After applying a minimum wage almost one in five gardens were financially viable. The results represent the most comprehensive measurements on home food gardens to date, and allow practical, evidence-based recommendations for diversification, time saving and smart irrigation practices to improve garden productivity and enhance the viability of UA.

Healthy and sustainable diets that meet greenhouse gas emission reduction targets and are affordable for different income groups in the UK

OBJECTIVE

To model dietary changes required to shift the UK population to diets that meet dietary recommendations for health, have lower greenhouse gas emissions (GHGE) and are affordable for different income groups.

DESIGN

Linear programming was used to create diets that meet dietary requirements for health and reduced GHGE (57 and 80 % targets) by income quintile, taking account of food budgets and foods currently purchased, thereby keeping dietary change to a minimum.Setting/ParticipantsNutrient composition, GHGE and price data were mapped to 101 food groups in household food purchase data (UK Living Cost and Food Survey (2013), 5144 households).

RESULTS

Current diets of all income quintiles had similar total GHGE, but the source of GHGE differed by types of meat and amount of fruit and vegetables. It was possible to create diets with a 57 % reduction in GHGE that met dietary and cost restraints in all income groups. In the optimised diets, the food sources of GHGE differed by income group due to the cost and keeping the level of deviation from current diets to a minimum. Broadly, the changes needed were similar across all groups; reducing animal-based products and increasing plant-based foods but varied by specific foods.

CONCLUSIONS

Healthy and lower-GHGE diets could be created in all income quintiles but tailoring changes to income groups to minimise deviation may make dietary changes more achievable. Specific attention must be given to make interventions and policies appropriate for all income groups.

Does Urban and Peri-Urban Agriculture Contribute to Household Food Security? An Assessment of the Food Security Status of Households in Tongaat, eThekwini Municipality

Regardless of the steady increase in the economic growth of South Africa, poverty levels and food insecurity have not declined as one would have anticipated. Urban and peri-urban agriculture (UPA) presents an opportunity as a livelihood strategy to alleviate poverty and ensure household food security within the urban and peri-urban spheres. However, less research has been done in this area to discover the contribution of UPA on households’ food security. This paper assesses the food security status of households that practised any form of UPA activities (later on referred to the rest of this paper as UPA practising households) and those that did not (later on referred to the rest of this paper as non-UPA practising households) within the Tongaat peri-urban area of eThekwini Municipality. The specific objectives of the paper are to estimate the household food security status of the UPA practising households vis-à-vis the non-UPA practising households and to elicit the reasons associated with the practice of UPA activities. Two hundred and eight (208) households (that is 109 and 99 UPA and non-UPA practising households respectively) were selected using a stratified random sampling procedure. The Household Dietary Diversity Score (HDDS) and Household Food Insecurity Access Score (HFIAS) measures were employed to estimate a household’s food security status. A probit regression analysis was used to elicit the reasons associated with the practice of UPA activities by households. A non-parametric independent samples test (Mann-Whitney U) was used to compare whether there were significant differences between the two groups. A Pearson Chi-Square test reveals that the employment status, access to arable land, land tenure (ownership rights or arable land) and household monthly income variables were statistically significantly associated with the food security status (in terms of HDDS) of households. The results from the HDDS tool, show that a greater proportion (54%) of the UPA practising households consumed >6 food groups (deemed to be food secure in terms of dietary access) as compared to their counterparts, the non-UPA practising households (40%) in the same food group. However, the Mann-Whitney U test (U = 5292, p = 0.808) show that there was no significant difference from this data in terms of the dietary diversity (HDDS) of the two groups. The HFIAS measure reveal that a greater proportion (about 72%) of the UPA practising households indicated that they never or rarely worried about food shortages (deemed to be food secure in terms of food access) as compared to their counterparts—the non-UPA practising households (about 61%) that never or rarely worried about food shortages. The Mann-Whitney U test (U = 4118.5, p = 0.001) show that there was a significant difference in terms of food access (HFIAS) of the two groups. Overall, the results show that although UPA practising households seemed to be better off in terms of food access as compared to the non-UPA households, the results are inconclusive or show no evidence that a significant difference existed concerning dietary diversity of the two groups. The probit regression analysis shows that the variable arable land size (p = 0.000) has a positive correlation with the practice of any UPA activity. In order for UPA to enhance the household food security status (particularly in terms of dietary diversity) within the peri-urban spheres, an integrated approach (with agricultural land support from government and city planners) together with the diversification of high-value UPA activities by households is paramount.

Water Use Efficiency in Urban Food Gardens: Insights from a Systematic Review and Case Study

Water use and the cost of water are key factors when considering the net value of urban agriculture (UA). This systematic review critically evaluates past and recent UA yield research from the perspective of water use efficiency. A systematic literature search was conducted using the databases Scopus, ProQuest Agriculture and Environment, and Web of Science for references from 1975 to 2018, with 25 articles meeting the inclusion criteria. Of these, only five articles had actively collected UA water use data, all on purpose-built experimental gardens. Considering the scarcity of UA water use efficiency and water measurement literature, South Australia is presented as a case study to demonstrate the considerable diversity of water pricing, water sources and irrigation methods available to urban food growers. The practical challenges of garden placement and the wide variety of cultivation techniques, water sources and irrigation methods are reviewed. Four equations to calculate the water use efficiency (WUE) of UA are proposed and demonstrated. Collection of additional UA water use data would support more robust evaluations of the water use efficiency and economic implications of different cultivation techniques. Further work in this field will enable a realistic understanding of the current and future contribution of UA to our society.